Method of mordanting and union



UNITED STATES PATENT OFFICE METHOD OF MOR-DANTING AND UNION DYEING Edward S. Chapin, Boston, Mass.

No Drawing.

Application January 31, 1936,

Serial No. 61,753

149 Qlaims.

This invention relates to a process of union dyeing, that is a process of dyeing textile materials and/or fabrics comprising a mixture of different fibers such as cotton, wool, rayon, silk, and other fibers.

One object of the invention is to provide a novel process involving the preparation by pretreatment or mordanting and the union dyeing of the mixed materials and/or fabrics to produce products in which the dyeings are-fast to water, to wet hot pressing against white fabrics, and in many instances to perspiration and to other agencies which involve resistance to the action of Water, soap, steam, and saline solutions.

A further object of the invention is to provide a novel process of union dyeing which is adapted to facilitate better control of the dyeing operation and to enable more satisfactory dyeing of the constituent fibers of the mixed materials and/or fabrics and of the materials and/or fabrics as a whole, than other processes of which I am aware.

A still further object of the invention is to provide a novel process of preparing mixed materials and/or fabrics for subsequent dyeing, in order to fix the colors in the dyed products.

With these general objects in view, and such others as may hereinafter appear, the invention consists in the process and steps thereof hereinafter described and particularly defined in the claims at the end of this specification.

The permanency of color in dyed fibers as to resistance to water, to perspiration, to wet hot pressing against white, and to other similar conditions which involve resistance to soap, steam, and saline solutions, is of great importance to the textile industries.

Especially is this true of materials and/or fabrics having mixed fibers, such as goods made from a combination of'cotton and wool and similar materials and/or fabrics, which may also contain rayon, silk, and other fibers. With these union materials and/or fabrics the securing of water fast results has prior to my invention required long and complicated processes, frequently resulting in off shade colors and unsalable products. After-treatments have sometimes been utilized but these change the shade of the goods, or otherwise injure the goods, and have not in general, made the materials and/or fabrics satisfactorily water fast.

Satisfactory water fastness could be secured by the use of expensive dyes and special manufacturingand special dyeing operations. This, however, would make the fabrics too expensive for ready sale to the general trade and particularly to the medium and lower priced trade, and accordingly the practice has been to use low priced, though unfast, union dyes. These union dyes are essentially mixtures of substantive (direct) dyes for coloring the cotton and the wool, as well as other fibers receptive to such dyes, and neutral dyeing (acid) dyes for coloring and toning the wool, as well as other fibers receptive to such dyes.

The ordinary union dyeing method as practiced prior to the present invention consists in running the materials and/or fabrics in a dye solution in the presence of common salt, and also adjusting the temperature of the dye-bath during the operation. The cotton of the fabric takes the direct dye in the main below the boiling point and the wool requires more nearly a boiling for dyeing it. Generally the practice has been to bring the bath to the boil, color the wool to shade at the boil,

and then fill up or dye the cotton to shade during a run-back or lowering of the temperature.

It has frequently been necessary to add extra cotton dye to the bath during the run-back in order to color the cotton deeply enough. Considerable practical skill is required to secure satisfactory results in which the cotton and wool are both well dyed, and in proper balance. The final step in such a process is to wash the goods in an attempt to remove the excess and unused dye and any dye loosely fixed on the fibers. However, the results obtained are dyed products that are not fast to steeping in water, wet hot pressing against white, to perspiration tests and similar agencies.

Thus, the great majority of commercial fabrics of mixed fibers containing cotton, as mens wear suitings, meltons, satinets, ladies dress goods, ladies cloakings, ski-clothes, linings, etc. have not been dyed by so called union dyes prior to my invention in such a manner as to make them fast to water, to Wet hot pressing against white, to perspiration and other similar agencies. As a result where such dyed products are made up into garments, the wearers experience staining of underneath garments and even of the body when the dyed garments become wet; and serious difiiculties result in repressing the wet garments from the looseness of the color. I

I have discovered that so-called union materials containing a plurality of different fibers such as cotton, wool, rayon, or silk and combinations thereof, may be successfully dyed with union dyes to produce dyed materials in which the dyes are fastto water and wet hot pressing against white fabrics by a process involving the pre-treating or mordanting of the materials with certain chromium compounds. After the materials have thus been pre-treated or mordanted, they may be dyed with advantageous results according to any usual or preferred union dyeing process. I prefer, however, to dye the materials in accordance with a novel process to be hereinafter described in detail, and the resulting dyed materials will possess a degree of color fastness when subjected to water, wet hot pressing against white and to perspiration, not possessed by union dyed materials of the prior art. In practicing the present process I have experienced satisfactory results using solutions of various chromium compounds, among which may be mentioned for example, chromium chromate, chromium fluoride, chromium acetate, and various chromium chloride liquors, but I prefer to utilize a solution which I am advised comprises essentially a chromium chromate, and in the form obtainable on the market under the trade name "Chrome Salt D.

The action of Chrome Salt D in pre-treating or mordanting union materials and/or fabrics is extremely rapid, especially with the wool of the goods at the elevated temperatures of the process; and this could form a fine precipitate, which deposited loosely on the materials and/or fabrics might produce in the subsequent dyeing unevenly dyed and poorly penetrated products. These products would also have a tendency to crock against white. Solubilizing agents as acetic acid and pure argol or bitartrate of potassium, or equivalents thereof, retard the action of the Chrome Salt D, maintain it in solution and prevent the formation of precipitates and further serve to feed the ChromeSalt D slowly into and on the fibres. In addition the pure argol or bitartrate of potassium, especially at the elevated temperatures of the process, acts to reduce the Chrome Salt D which assists in the uniform pre-treatment and penetration of the materials and/or fabrics. With the help of these agents goods are properly pretreated and mordanted; and in the subsequent dyeing solidly dyed and well penetrated products result and the tendency to crock against white is reduced to a minimum. For convenience of description pure argol or bitartrate of potassium and other equivalents thereof will be referred to as Chrome Salt or mordanting assistants. In accordance with the preferred process of pretreating or mordanting the materials and/or fabrics, the following procedure may be followed.

The proportions of reagents preferably utilized comprise:

3% Chrome Salt D 2% Chrome Salt assistant acetic acid 28% calculated on the weight of the goods.

The mordanting bath should be from fifteen to twenty times the weight of the goods and is first brought to F. The Chrome Salt assistant is dissolved separately in boiling water and added slowly to the mordanting bath. Then the acetic acid, well diluted, is added slowly to the mordanting bath and the goods are then run for a period of ten minutes in order to permit the Chrome Salt assistant and acetic acid to be thoroughly distributed throughout the goods. The Chrome Salt D is diluted with several volumes of water at F. and added slowly to the bath. The goods are then run for a period of about ten minutes and the bath is then brought to the boil in three-quarters of an hour and the boiling continued for a period of one-half hour to one hour after which the goods are washed thoroughly.

The use of the Chrome Salt assistant results in a condition very satisfactory for dyeing when the yellow tone of the goods has become a grayish green. The Chrome Salt assistant in mildly acid bath acts as a carrier of the Chrome Salt D and insures the deposition and reduction of the Chrome Salt D in and on the fibers of the goods which is quite essential to bring out the special features of the process. I

While the foregoing represents a typical process that may be employed in practice in the pretreatment of union materials and/or fabrics with chromium compounds, it is pointed out that other proportions of reagents than those above given may be found advantageous. It is further pointed out that other forms of chromium compounds aside from those above mentioned, which are analogous to and similar in action to chromium chromate may be utilized; and that other tartrates or equivalent compounds similar to or analogous to the action of argols; and that other acids similar to or analogous to the action of acetic acid can be utilized.

By this procedure the goods are mordanted by the chromium compounds and placed in a condition ready for dyeing with ordinary union dyes. The mordanting of the cotton component of the goods enables the cotton to be dyed more satisfactorily with the cotton dye than in the ordinary union dyeing process. Whereas heretofore in ordinary union dyeing it has frequently been difficult to color the cotton sufllciently deep in the presence of the wool, in accordance with the present process the cotton takes the dye by preference, and secondly the mordant on the wool acts like a resist to the cotton dye so that the wool absorbs the dye slowly even at a boil. In this respect the present process is clearly distinguished from the ordinary union dyeing process in which the wool absorbs the dye quickly at or near the boil, stealing from the cotton with the result that there has always been the danger of the wool being over-dyed and the cotton under-dyed, producing unsalable results.

The preferred procedure which it is recommended to be followed in dyeing'the mixed materials and/orfabrics after they have been mordanted in the manner described, includes the use of the same dyes as may be used inthe ordinary union process as practiced prior to my invention, and a dye bath of from ten to fifteen times the weight of the goods is desirable. The dye bath is first raised to 110 F. The dye is dissolved separately, the usual precautions being taken to insure its complete solution and in adding it to the bath. Fifteen percent of common salt is added to the bath, which is run ten minutes at 110 F., and then brought to a boil in three-quarters of an hour. It is preferred to add a further 15% common salt at 170 F. to insure continuous and complete dyeing of the cotton color on the cotton. If the dye bath is unavoidably long, the salt should be increased in the ratio of the dilution. The cotton should be on shade at the boil, but if not, extra cotton dye or salt is added as may be deemed necessary and the boiling continued until the cotton is on shade. When the cotton is on shade the wool will be underdyed. The steam is then turned off, the bath allowed to cool to F., and there upon from /2 to 1%% of formic acid well diluted in water, is added slowly to the bath. The bath is again brought to a boil and the boiling continued until the wool is on shade. The color of the cotton will usually be unchanged by the boiling in the formic acid and additional wool dye may be added to the bath if necessary to bring the wool to shade. The goods are finally washed thoroughly.

In the present process the mordanting of the cotton causes the cotton color to go on the cotton by preference and it is quite possible to dye the cotton of the union goods to shade in the salt bath in coming to the boil and no supplemental steeping and dyeing of the cotton is required. Once the color is on the cotton it stays there and does not come off in subsequent boiling or washing. The mordant on the wool acts as a resist toward cotton dyes, and the wool can be dyed slowly at the boil. These features eliminate the danger of overdyeing the wool and give an almost perfect control of this diificult stage of the union dyeing process.

The ease of producing union dyed products fast to Water by the process herein described carries with the chemical characteristics of the dyes. Thus the direct brown dye, Color Index No. 420, which is largely employed in cheap union brown mixtures is readily made water fast by relatively small percentage of Chrome Salt D, two or three pounds of chrome salt D in the mordanting bath per one hundred pounds of goods being sufiicient to fasten an'equal quantity of dye. This simple relationship applies in most cases. There are, however, certain dyes hard to fix. Thus the direct blue, Color Index No. 401, which is a favorite component of cheap navy blue union mixtures requires a heavy mordanting to produce water fast results, and in practice ten or fifteen pounds of Chrome Salt D in the mordanting bath per one hundred pounds of material is suflicient for an ordinary or deep navy shade. Another sample of a dye hard to fix comprises the direct red, Color Index No. 278, and in this instance a heavy mordant is recommended.

In connection with the practicing of the present process of dyeing, utilizing dyes such as direct blue, Color Index No. 401, and direct red, Color Index No. 278, I have discovered that the use of excessive amounts of the mordant such as Chrome Salt D may be avoided by mordanting with the usual proportions of Chrome Salt D and subjecting the dyed materials to an after treatment with a fixing composition preferably a modified alum or aluminum sulphate, the same comprising an invention made by me jointly with Walter C. Durfee and forming the subject of a copending application Serial No. 115,982. In the co-pending application it is explained that the desirable effects of alum or aluminum sulphate in fixing the color of the dye in dyed materials, and especially union dyed materials and/or fabrics may be successfully utilized by suitably modifying the alum or aluminum sulphate with various reagents or compounds. The following are illustrative examples of the proportions and reagents which may be utilized in typical fixing compositions for use in practising the present process:

Formula! Parts Alum 46 Argols 4 Common salt 50 Formulaz Parts Alum f- 48 Argols 4 Basic chromium sulphate 18 Common salt- 30 Formula3 Parts Alum 48 Calcium acetate 12 Basic chromium sulphate -1 12 Argols 4 Common salt 24 Formula4 Parts Alum 48 1 Calcium acetate 18 Basic chromium sulphate 12 Argols .4 Common salt 18 Formula5 Parts Alum 33 Calcium acetate 28 Basic chromium sulphate 12 Argols 4 Common salt 23 considerably in degree. It is preferred to utilize a type of fixing composition in which the sulphuric acid ofthe alum or aluminum sulphate is well buffered without diminishing unduly the fixation.

In this connection it is pointed out that other proportions than those given in the typical formulae of fixing compositions may be found advantageous. It will also be understood that other forms of aluminum salts and their equivalents and also zinc salts which are to some extent analogous to and similar in action to alum can be utilized: that various forms of chromium salts which are analogous to and similar in action to the chromium salt set forth above can be utilized; and that other acetates such as sodium acetate and magnesium acetate; and that other tartrates or equivalent compounds similar to or analogous to the action of argols; and that other equivalents of common salt as Glaubers salt can be employed.

The dyeing kettle with the well-washed goods is filled with cold water and ten to fifteen percent brought slowly to -110 F. and the fixing then continued for fifteen to twenty minutes. Fixing at a lower temperature may be possible, depending upon the character of the dyed material or fabric, and the more suitable conditions as to temperature for any particular material can be easily determined by practical trial. Thereafter the goods are washed and as a result of the fixing treatment those dyes which are dimcult to fix may be made water fast.

It will be understood that the words cotton and wool as used throughout the specifications and claims are typical of and intended to define fibers that act in a general way similarly to cotton and wool; and that the words, cotton and wool union materials and/or fabrics are representative of and intended to define a great variety of commercial union materials and /or fabrics,

consisting of two or more different fibers, and composed in a general way similarly to, cotton and wool union materials and/or fabrics. Thus, rayon behaves in a general way similarly to cotton; and mohair to wool: and union materials and/or fabrics composed of cotton, rayon and wool; cottonand mohair; rayon and. wool; cot ton, wool, and silk; and various other blends may be dyed most emciently by the present process.

The present process possesses a number of important commercial advantages as will be appreciated from the above description thereof. The control features enable dyeing the "cotton and the wool" to any desired shade with facility and assurance. Further when the "cotton is dyed to shade it does not wash all as in ordinary union dyeing and consequently deeper richer shades can be secured by the present process. The cotton dyes fix readily on the cot- C ton and thus it is not necessary to use an excess of cotton dyes to color the cotton. This is a considerable advantage as it produces economies in the use of cotton dyes. The dyes both for the cotton and the "wool are also more completely utilized or exhausted on the union materials and/or fabrics by the present process. Aside from producing economies, the greater exhausting of the dyes on the union materials and/or fabrics,

results in a further practical advantage. The

goods after dyeing wash more readily and cleaner. Finally a very important advantage in practical operation, the present process enables great sureness in securing the desired dyed effects on the individual fibers and on the fabrics as a whole, thus reducing to a minimum the necessity of redyeing or retreats" where union materials and/ or fabrics are oil-shade.

As used throughout the specification and claims, the term fix is intended to define the rendering of the dye in the dyed fibers permanent with respect to its resistance to water, to wet hot pressing against white, sometimes to perspiration and to other similar conditions which involve resistance to steam and saline solutions. It will also be understood that the term "boil" or boiling" is intended to define thetemperature generally regarded as boiling by the dyeing trade but which because of the heating arrangement of the dye kettle usually varies from ZOO-205 F. As used throughout the claims, the term "vegetable fiber" is intended to define fibers which dye similarly to cotton, and the term "animal fiber" is intended to define fibers which dye similarly to wool.

While the preferred process has been described. it will be understood that the invention may be embodied in other processes within the scope of the following claims.

Having thus described claimed is:

1. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comthe invention, what is prises treating the materials with a mordant comprising a water soluble chromic salt, and then dyeing the materials with union dyes.

2. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water soluble chromic salt and a mordanting assistant, and then dyeing the materials with union dyes.

3. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water solution of chromium chromate, and then dyeing the materials with union dyes.

4. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water solution of chromium chromate and a mordanting assistant, and then dyeing the materials with union dyes.

5. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water soluble chromic salt, and then dyeing the materials with union dyes. adding formic acid toward the end of the dyeing operation to complete the dyeing of the animal fiber.

6. A process for the dyeing of union materials composed of animal and vegetable fibers in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water solution of chromium chromate, and-then dyeing the-materials with union dyes, adding formic acid toward the end of the dyeing operation to complete the dyeing of the animal fiber.

7. A process for the dyeing of union materials composed of cotton and wool in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water soluble chromic salt, and then dyeing the materials with union dyes.

8. A process for the dyeing of union materials composed of cotton and wool in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water solution of chromium chromate, and then dyeing the materials with union dyes.

' 9. A process for the dyeing of union materials composed of cotton, wool and rayon in order to render the dyeings .fast to water which comprises treating the materials with a mordant comprising a water soluble chromic salt, and then dyeing the materials with union dyes.

10. A process for the dyeing of union materials composed of cotton, wool and rayon in order to render the dyeings fast to water which comprises treating the materials with a mordant comprising a water solution of chromium chromate, and then dyeing the materials with union 

